Question

tìm x:

a) 5^x . 5 = 625

b) 3^x = 9.27

c) (x-6)² = 9 

 

Answer 1

a) \(5^x.5=625\)

\(\Rightarrow5^x=125=5^3\)

\(\Rightarrow x=3\)

b) \(3^x=9.27\)

\(\Rightarrow3^x=3^2.3^3=3^5\)

\(\Rightarrow x=5\)

c) \(\left(x-6\right)^2=9\) .

\(\Rightarrow\orbr{\begin{cases}x-6=-3\\x-6=3\end{cases}}\Rightarrow\orbr{\begin{cases}x=3\\x=9\end{cases}}\)

Answer 2

5^x.5=625

=>5^x.5=5⁴

=>5^x=5⁴:5

=>5^x=5^4-1

=>5^x=5³

=>x=3

Answer 3

a/ 5^x . 5 = 625  => 5^{x + 1} = 5⁴  => x + 1 = 4  => x = 3

b/  3^x = 9 . 27  => 3^x = 3² . 3³  => 3^x = 3⁵  => x = 5

c/ (x - 6)² = 9  => x - 6 = 3 hoặc x - 6 = -3  => x = 9 hoặc x = 3

Answer 4

3^x=9.27

=>3^x=3².3³

=>3^x=3²⁺³

=>3^x=3⁵

=>x=5

Answer 5

(x-6)²=9

Mà: 3²=9 hoặc (-3)²=9

=>x-6=3 hoặc x-6=-3

=>x=3+6 hoặc x=-3+6

=>x=9 hoặc x=3